Optical fiber unit and optical fiber unit manufacturing method

An optical fiber unit manufacturing method comprising:

• preparing an intermittently-connected optical fiber ribbon comprising optical fibers, including:
• a first optical fiber and a second optical fiber that is longer than the first optical fiber, wherein
• the second optical fiber deforms in a thickness direction of the intermittently-connected optical fiber ribbons with respect to the first optical fiber, and
• the following conditions are satisfied:
• C
• >
• 100
• ×
• {
• (
• 2
• ⁢
• Y
• b
• )
• 2
• +
• 1
• -
• 1
• }
• and
• c<0.05, where
• b is an interval, in a length direction, between connection parts that connect the first optical fiber and the second optical fiber,
• c (%) is a fiber length difference of the second optical fiber with respect to the first optical fiber, and
• Y is an interval between the optical fibers in a ribbon width direction;
• and
• assembling intermittently-connected optical fiber ribbons including said intermittently-connected optical fiber ribbon including said second optical fiber.